This invention relates to wireless communications systems, and more particularly, to wireless communications systems that operate under outdoor environmental conditions.
Some known communications systems are designed, manufactured, and implemented for operation that is suitable for indoor environmental conditions (e.g., in buildings, indoors, etc.). Such systems include wireless local area network communications systems (xe2x80x9cwireless LANSxe2x80x9d) that are typically designed, manufactured, and implemented in indoor applications where, for example, wireline installation may not be practical. Such applications include warehouse inventory tracking, portable point of sale, shipping and receiving, packages tracking, etc.
Vendors may have manufactured wireless LANs and components thereof for indoor installation and operation where wireless LANs may typically operate in air conditioned or sheltered offices, warehouses, retail stores, etc. The demand for outdoor environmental operation of such systems has increased over recent times. Outdoor operation may require equipment to be appropriately operational in a wide range of environmental conditions. Such environmental conditions may include extreme weather conditions, such as direct sunlight, tropical conditions, extreme temperatures, rain, snow, etc. Known wireless LANs and components thereof (e.g., access points) are not known to be capable of operating and are not known to be designed to operate in such outdoor weather conditions. Systems and components that meet such demands may be needed without substantially raising the cost, complexity, efficiency, etc. of the system and/or components thereof.
The IEEE 802.11 communications standard as published has been used by some vendors to provide interoperability between wireless LAN equipment. The 802.11 standard specifies communications protocols in which information is transmitted in packets. The standard specifies features such as packet size, packet content information, data rates, roaming, etc. In such known systems, several remote terminals may be in communications with a single access point to receive and transmit information. The standard as published specifies a communications medium that is shared by transmitters (e.g., an access point and one or more remote terminals). The primary type of information that was initially transmitted in systems that were designed to the 802.11 standard as published was information such as barcode information, point of sale information, package tracking information, etc.
In accordance with the principles of the present invention, an outdoor access point may be provided for use in wireless local area network communications systems. The outdoor access point may include a portable housing.
The portable housing may include a case that may be adapted to receive an indoor access point (e.g., an access point that is suitable for indoor environment operation) and to fixedly hold the indoor access point. The case may be a rugged case that may have characteristics such as being substantially water-proof (when the case is closed), being substantially oil-proof (when the case is closed), having desired shock absorbency, etc. The case may be double-skinned with insulation being provided between the interior and exterior skin of the case.
The portable housing may include a conduit through which electricity may be passed between an interior envelope that is formed when the case is closed and the exterior of the case. The conduit may be substantially water-proofed. The conduit may be considered to be part of the case. Together the conduit and the case provide water-proofing for the portable housing. The conduit may include a gland that is substantially water-proofed and an opening in the case to which the gland has been attached. Cables and cable connectors may be passed through the gland and a tubing may be used in the gland to substantially prevent water from entering the interior envelope of the case through the gland.
The portable housing may include circuitry that includes a sensor that is configured to sense when the temperature in the interior of the portable housing is approximately outside a threshold range (e.g., 0xc2x0 to 38xc2x0 Celsius). The threshold range may be determined based on the temperature range in which the indoor access point may be operable (e.g., 0xc2x0 to 40xc2x0 Celsius).
The portable housing may include a heat exchanger that is responsive to the sensor. The circuitry may include control circuitry that responsive to the sensor controls the heat exchanger. The heat exchanger may have a thermal conduction connection through the case between the interior of the case and the case exterior. The heat exchanger may be controlled to transfer heat into the interior envelope or transfer heat away from the interior envelope of the case of the portable housing. The heat exchanger may be controlled by the control circuitry in response to the sensor to regulate the temperature in the interior envelope of the case approximately within the predetermined threshold range which may be a temperature range that is suitable for operating the indoor access point.
The heat exchanger may include air circulating devices in the interior envelope of the case that, responsive to the sensor, may circulate air in the case. The heat exchanger may include a fan for cooling a power supply when the outdoor access point includes a power supply in the interior envelope of the case. If desired, power may be supplied using an external battery, solar panel, etc.
In one aspect of the invention, the heat exchanger may include two internal thermal conductors, two external thermal conductors, two Peltier devices, and two thermal connectors. The two internal thermal conductors may be in the interior envelope of the case with an air-circulating device mounted on top of each. The two external thermal conductors may be on the outside of the case and may be attached to an outside surface of the case opposing the two internal thermal conductors. Two openings may have been formed in the shell of the case with each opening being in between one of internal and external thermal conductors. One of the two Peltier devices and one of the thermal conductors may be substantially within each of the openings and may be sandwiched between the thermal conductors at each opening. The Peltier devices may be electrically connected to the control circuitry and may be responsive to the sensor and the control circuitry. At each opening one of the internal thermal conductors, one of the thermal connectors, one of the Peltier devices, and one of the external thermal conductors may be in a heat transfer relationship. The interior envelope of the case may be appropriately heated or cooled based on the direction of a current that may be provided to the Peltier device when the sensor may have sensed that the temperature in the interior envelope is approximately outside the predetermined threshold range.
In another aspect of the invention, the heat exchanger may include an internal thermal conductor, an external thermal conductor, two Peltier devices, and two thermal connectors. The internal thermal conductor may be in the interior envelope of the case with the air-circulating devices mounted thereon. The external thermal conductor may be on the outside of the case and attached to an outside surface of the case opposing the internal thermal conductor. These openings may have been formed in the shell of the case with each opening being in between the interior and exterior thermal conductors. One of the Peltier devices and one of the thermal conductors may be substantially within each of the openings and may be sandwiched between the thermal conductors at each opening. The Peltier devices may be electrically connected to the control circuitry and may be responsive to the sensor and the control circuitry. At each opening, the internal thermal conductor, one of the thermal connectors, one of the Peltier device, and the external thermal conductors may be in a heat transfer relationship. The interior envelope of the case may be appropriately heated or cooled based on the direction of a current that may be provided to the Peltier device when the sensors have sensed that the temperature in the interior envelope is approximately outside the predetermined threshold range.
The portable housing may include a back plate that may fit different adapters for mounting the housing in different environments. The adapters may include a wall-mounting adapter or a pole-mounting adapter for mounting the portable housing on a wall or a pole, respectively. The back plate may be attached to an exterior surface of the case.
The portable housing may include an antenna that is external to the case. The antenna may be attached to the back plate and may have an electrical connection to the interior envelope of the case for the indoor access point.
The portable housing may include a shade for protecting and shading the case. The shade may include connecting bars that connect the shade to the case and that include pivots for raising or lowering the shade. The shade may be made of a plurality of panels. The panels may have a supporting layer (e.g., a layer made of aluminum) and an ultraviolet light protecting layer. The light protecting layer may be positioned to be in the layer that is in the line of path of sunlight when the shade is raised. The protecting layer and the supporting layer may be configured to include an air gap between the two layers.